This invention relates to a system and apparatus for water conditioning, more particularly to such a system and apparatus for water softening for domestic, or industrial, use and it is an object of the invention to provide an improved system and apparatus including components thereof of this nature.
Automatic water softening systems and apparatus in the sense that softened or treated water is continuously available are well-known. In this respect reference may be made to U.S. Pat. No. 3,891,552 Prior et al, issued on June 24, 1975 for Control Valve for Water Softeners. In this patent and in other known systems, it is known to provide two softener tanks associated with a salt and brine supply so that when the water softening capability of one of the tanks is exhausted the system is automatically switched to the second tank which in the meantime has been regenerated. During the subsequent use of the regenerated tank the exhausted tank is recharged or regenerated and it is therefore available when the immediate tank in use has been exhausted.
The prior art water softeners usually are of the ion exchange type in which hard water flows through a recharged tank including a resin or, mineral, which has an abundant supply of soft water ions in it which are exchanged on the surface of the mineral for the hard water ions of the supplying hard water. Hard water ions may be of calcium and/or magnesium typically whereas soft water ions typically are sodium ions. After a certain number of gallons of water have flowed through the tank in use the softening ability of the mineral therein has become exhausted, which is to say there are no longer any soft water or sodium ions available to replace the hard water or calcium or magnesium ions. At this point through some sensing mechanism the exhausted tank is switched out of the user circuit and the waiting recharged (regenerated) tank is switched into the circuit and continues to supply softened water. The exhausted tank is then connected into apparatus for regenerating the exhausted mineral in it. In this process removing, or flushing out, the hard water ions of magnesium and calcium and resupplying the mineral with an inventory of soft water or sodium ions takes place.
Typically, known systems require about one hour, or so, for recharging the exhausted tank while the recharged tank that is in use is capable of supplying an ordinary household with softened water for a period of several days depending upon the amount of use. Thus whenever the tank in use becomes exhausted the regenerated tank is ready to be substituted therefor.
Some well-known prior art systems for softening water for domestic use utilize a single tank in which the water softening mineral is disposed and when the softening effect has been exhausted the mineral in the tank is recharged. During the recharging, or regeneration, cycle the tank is not available for supplying softened water for domestic use because at that point, the water available is hard, or filled with salt, depending upon the phase of regeneration that the tank is in. Water softening cycles or systems of such well-known single tank operations have included upflow or counterflow, backwashing under a substantial rate of flow but at a low enough rate so that the mineral is not flushed out of the tank. Such rapid flow backwashing fluffs the mineral and eliminates any tendency for the rinsing to become channelized and thus inefficient. The upflow or counterflow is opposite to the downflow direction of the water when the tank is in service. Likewise, such prior single tank systems have included brine introduction in a downflow, or service flow, direction at a relatively slow rate of flow in order to introduce the brine as needed and without flushing it through unnecessarily. After the brine has been introduced in the down flow direction at a relatively slow rate a rinse is carried out in the same downflow direction to rinse out the brine that remains after having served its purpose by exchanging soft water ions for the hard water ions. After the slow rate of rinse flow such prior art systems have carried out a fast flow purge also in the down flow direction to eliminate any residue of salt in the mineral. The down flow purge can be at a fast rate because the mineral is being pushed down into the tank and therefore is not subject to being flushed out or lost. The downflow direction is of course the same as the service flow direction. In all of these phases of regeneration the water used is hard water from the supply inasmuch as there is no soft water available for this purpose in any event. This is a serious problem existing with single tank systems along with the fact that the tank is not available for supplying soft water during the regeneration period of one or two hours.
In such prior systems the only phase of regeneration that is conducted with soft water is the brine make-up cycle so that the brine available for the next recharge of the exhausted tank is with soft water brine.
As indicated above, two tank systems are known to the prior art which eliminate certain of the disadvantages of a single tank system. For example, there is no delay in having soft water available when the tank in serivce has to be regenerated because the regenerated tank is there and is placed in service immediately. Also, in such two-tank systems soft water is available for all of the regeneration functions including rinsing, brine introduction, and purging as well as brine formation.
In such two-tank systems the direction of flow in the tank in service is downflow in order to have the flow go against the compacted mineral thereby achieving better contact of the hard water with the mineral and resulting in improved filtering and the like. Such known systems have not included an upflow or counterflow backwash at a relatively strong rate, but have included brine injection at a relatively slow rate in an upflow or counterflow direction and have continued rinsing at the same slow rate for a period of time. The latter is followed by a relatively fast but controlled backwash flow rate in an upflow or counterflow direction so that the mineral is not washed or flushed out of the tank. In such systems the fast backwash rate cannot be as great as the purge or rinse cycle of the single tank apparatus because of this fact. A possibility exists therefor in such known two-tank systems that there may be some residual salt taste in the softened water shortly after the regeneration has taken place.